Yeah, I mean Sli is out way before Crossfire is, and well it's all good and dandy you getting an X850XT for gaming, but to put it into crossfire you have to buy yet another one, which is a great marketing ploy from ATI. It will boost their sales on their higher end cards by a hell of a lot....
But the only advantage of Crossfire over SLi is that it's backwards compatible with any ATI card as long as one of the cards is Crossfire enabled. Now that's great, but ask around and you're not going to find many people who have dual 7800GTXs because well it's just a waste of money because one 7800GTX already owns any game out at the moment. Dual 7800GTXs is overkill, just like dual X850XTs (one X850XT pretty much rns any game out at the moment at full graphics anyways). They alo won't come cheap as they are brand new on the market with extra technology on them. Also, as I said earlier, the only advantage of Crossfire over SLi is that it's backwards compatible, but seriously, who is going to team up an X850XT with an X800? You're not going to get a stellar performing machine considering the amount of money you are going to have to put it, and yet again, it's overkill. SLi and Crossfire should only really be used by people who own one mid-range card (like a 6600/6800 or a 9800/X800).
The only thing I don't know is how far back the Crossfire can go. I mean, can it handle the ultimate power of two 9600s???
Personally, if you're an ATI fan, I'd wait for Crossfire to become more popular and wait for prices to drop. Fortunately, nVidia actually care about their customers as SLi was released around the time of the 7800GTX which stops people going out and buying a non SLi 7800GTX card, and then to find out you're gonna have to buy another one just allow them to go into SLi mode. ATI really did slap their fans in the face by releasing the X850XT with full knowledge of Crossfire coming out, making ATI fans buy yet another X850XT which is overkill for this time in gaming. If I was you, I would have waited for the Crossfire enabled X850XT so I can combine it with another ATI card that is cheaper for added performance (but like I said, it's a waste of money at the minute).
Sorry to go on, but as you can guess, I'm an nVidia fan and any chance to shoot down ATI, I take